A liquid sealed engine mount is publicly known and provides high damping through an orifice communicating between a primary liquid chamber and a secondary liquid chamber. When vibration which applies pressure from the primary liquid chamber is a positive pressure side and the vibration in the reverse direction is a negative pressure side, a conversion of the vibration from the positive pressure side to the negative pressure side at the time of great force input develops the negative pressure temporarily within the primary liquid chamber due to the delay of a return of a hydraulic liquid from the secondary liquid chamber to the primary liquid chamber, whereby to produce bubbles in a hydraulic liquid. When these bubbles burst, there may be cases where a cavitation noise producing an extraordinary noise is created.
As an example of a structure for preventing this cavitation noise, there is publicly known the device of the type that comprises an elastic diaphragm provided in a partition member, a cylindrical relief valve provided in a center of the elastic diaphragm, an axial hole of the cylindrical relief valve being configured to serve as a relief hole, a seal section provided on a support member for supporting a secondary liquid chamber side of the elastic diaphragm so as to contact the relief valve to close the relief hole, and a through hole which opens into the secondary liquid chamber side, being formed around the seal section. In this type of the device, on the positive pressure side, the leak of the hydraulic liquid from the primary liquid chamber to the secondary liquid chamber is prevented by allowing the relief valve to come in close contact with the seal section in such a way as to close the relief hole, while, on the negative pressure side, the relief valve is brought out of contact with the seal section and the hydraulic liquid is allowed to leak from the secondary liquid chamber through the relief hole to the primary liquid chamber, whereby the cavitation is prevented.